CCTV - technical definition

(Closed Circuit TV) A surveillance system comprised of cameras, recorders and displays that is used to monitor activities in a store or company. Earlier CCTV systems used a single VHS tape machine for each camera, specialized "quad" VCRs that recorded four low-resolution images or time-lapse recorders that handled multiple cameras. Although analog cameras are still widely used, the VHS tape machines have given way to digital video recorders (DVRs) with multiple composite video inputs.

The DVR and NVR
Increasingly, digital "network cameras" are used in CCTV that transmit over an Ethernet network. Offering higher resolution, the network camera also provides greater installation flexibility. For more details, see network camera.